1. Field of the Invention
This invention relates to an image forming apparatus such as an electrophotographic type analog copying machine, a digital copying machine, a color copying machine, a printer or a page printer.
2. Related Background Art
The speedup of the image forming speed in an electrophotographic type image forming apparatus has heretofore been carried out by effecting, in addition to the supply and conveyance of a transfer material, all of a series of operations such as image forming processes, i.e., latent image formation, development, the transfer of a toner image to the transfer material (e.g. a transfer sheet or the like) and further, fixing, at a high speed. For example, to realize an apparatus capable of forming 60 sheets of images per minute, relative to an apparatus capable of forming 30 sheets of images per minute, there has been adopted a construction in which in addition to the supply and conveyance of the transfer material, image forming processes are carried out with a driving speed necessary therefor set to double.
In the above-described example of the prior art, however, in order to realize high-speed image formation, with the speedup of the sheet supply speed of transfer material supplying means for successively drawing out transfer materials supported on transfer material supporting means (e.g. a sheet supply cassette or the like), it has been necessary to provide inter-sheet taking into account a reduction in the accuracy of the interval between transfer materials during the continuous supply of the transfer materials, i.e., the inter-sheet interval (hereinafter referred to as the inter-sheet). Also, in addition to the conveyance of the transfer materials, it has been required to speedup the image forming processes and a large-scaled investigation has been required.
Thus, for example, in the latent image formation in the image forming processes, in a digital image forming apparatus, it is necessary to operate the image processing and latent image forming means thereof such as a laser at a high speed, and for example, when development is to be made from an apparatus capable of forming 30 sheets of images per minute to an apparatus capable of forming 60 sheets of images per minute, an image processing portion or the like of which the image clock frequency is doubled has been required. Also, in an analog image forming apparatus, it has been necessary to double the driving speed of an original scanner for scanning (reading-scanning) an original to be copied.
Further, in both of the digital and analog image forming apparatuses, the image forming processes such as the development and transfer of a toner image are the most important techniques, as it were, in an electrophotographic type image forming apparatus, and a long investigation time has been required before the construction and control technique thereof are determined, and there has been a problem to be solved that considerable resources are required for the development of an image forming apparatus resulting from high-speed image formation.